1. Field of the Invention
The present invention relates to a cleaning and drying method of and an apparatus for cleaning objects to be processed, such as semiconductor wafers and LCD (liquid crystal display) glass substrates etc., by immersing them in cleaning liquid, for example chemicals and rinsing liquid, and sequentially drying the objects cleaned.
2. Description of the Related Art
Generally, in the field for producing semiconductor devices, there is a widely adopted cleaning method where the objects to be processed, such as semiconductor wafers and LCD glass substrates etc.(referred to xe2x80x9cwafers etc.xe2x80x9d hereinafter), are successively immersed in a process bath filled up with the chemicals, the rinsing liquid or the like. In addition, a cleaning apparatus carrying out the above-mentioned method is equipped with a drying apparatus which dehydrates and dries the wafers etc. by contacting the surfaces of the wafers etc. after cleaning with dry gas of vapor of volatile organic solvent such as IPA (isopropyl alcohol) etc., for condensation or absorption of the vapor of the dry gas on the surfaces.
The conventional cleaning and drying methods of this kind are disclosed in Japanese Unexamined Patent Publication (kokai) No. 2-291128 and Japanese Examined Patent Publication (kokoku) No. 6-103686.
In accordance with the art disclosed in the former Publication No. 2-291128, the objects to be processed, for example the wafers are immersed and cleaned in the process bath where the cleaning liquid, e.g. pure water is overflowing. Thereafter, the cleaned wafers are slowly drawn up from the process bath by conveying means such as a chuck and simultaneously, the dry gas composed of vapor of volatile organic solvent, such as IPA (isopropyl alcohol) is supplied into the processing chamber to come in contact with the surfaces of the wafers and the cleaning liquid. That is, the elimination of moisture on the wafers and the drying of the wafers are executed due to the Marangoni effect.
While, according to the art disclosed in the letter Publication No. 6-103686, after cleaning the wafers in the processing chamber filled with the cleaning liquid, for example the pure water, the elimination of moisture on the wafers and the sequent drying are carried out by dry steam of cleaning fluid. In detail, the dry steam is supplied so as to directly remove the pure water from the surfaces of the wafers at such slow replacing speed that the pure water or the dry steam is not substantially removed by evaporation of drops.
In the prior art cleaning and drying methods mentioned above, however, it is necessary to lengthen the contact time of the pure water, the wafers etc. with the dry gas because both of the methods are together directed to completely eliminate the moisture on the wafers by causing the dry gas to contact with the surfaces of the wafers and the cleaning liquid in view of the Marangoni effect and the direct replacing. Therefore, in these conventional methods, there is a drawback of requiring a lot of time for the drying process, thereby causing the drying efficiency to be deteriorated and the great consumption of dry gas. In addition, the long-sustained contact of the wafers with the organic solvent gas, such as IPA, would cause resist films on the wafers to be dissolved into the organic solvent disadvantageously.
Accordingly, it is therefore an object of the present invention to provide a cleaning and drying method and a cleaning and drying apparatus, by which an improvement in the drying efficiency and a reduction in the dry-gas consumption can be accomplished.
According to the first feature of the present invention, there is provided a cleaning and drying method of drying an object to be processed, which has been immersed in cleaning liquid stored in a cleaning chamber for cleaning said object, in a drying chamber arranged above said cleaning chamber, said method including steps of:
supplying dry gas into said cleaning chamber after cleaning said object;
draining said cleaning liquid under condition that said object is fixed in said cleaning chamber, while contacting said dry gas with said object to dry said object in a first drying process; and
moving said object to said drying chamber after the first drying process and sequentially supplying dry gas into said drying chamber to dry said object in a second drying process. In the above-mentioned method, both said dry gas used in the first drying process and said dry gas used in the second drying process may contain volatile organic solvent. Alternatively, said dry gas used in the first drying process may contain volatile organic solvent, while said dry gas used in the second drying process may be inert gas. Further, said moving step of moving said object to said drying chamber can be carried out after said cleaning liquid has been drained or a level of said cleaning liquid has been lowered below said object to be processed.
According to the above-mentioned method, by moving the object into the drying chamber after the first drying process to contact the dry gas with the object and subsequently contacting the dry gas with the object again, it is possible to prevent much moisture from adhering to the object moved into the drying chamber and dry the object by its contact with very little dry gas supplied into the drying chamber. Therefore, owing to the adoption of the first and second drying processes, it is possible to effectively make use of a small amount of dry gas without using a great amount of dry gas at a time, whereby the reduction in consumption of dry gas and the improvement in drying efficiency can be accomplished.
According to the second feature of the present invention, in the cleaning and drying method of the first feature, closing means for insulating said cleaning chamber and said drying chamber from each other is arranged between said cleaning chamber and said drying chamber and said closing means is closed during drying said object in the second drying process.
Thus, the second drying process can be executed under condition that the closing means is closed, whereby it is possible to reduce the consumption of dry gas furthermore. Additionally, the provision of the closing means allows the cleaning liquid in the cleaning chamber to be exchanged for new liquid during the second drying process in the drying chamber, so that the cleaning process for the next object can be carried out as soon as the second drying process has finished.
According to the third feature of the invention, alternatively, the above closing means may be closed during drying said object in the first drying process. Also in this case, it is possible to reduce the consumption of dry gas required for the first drying process, furthermore.
According to the fourth feature of the invention, alternatively, the above closing means may be closed except that said object is being moved between said cleaning chamber and said drying chamber.
Also in this case, since the first drying process can be executed while closing the closing means, it is possible to further reduce the consumption of dry gas required for the first drying process, similarly.
According to the fifth feature of the invention, the cleaning and drying method of the first feature is characterized by a further step of blowing dry gas against said object during moving said object from said cleaning chamber to said drying chamber. Thus, owing to the increased time of the object""s contact with the dry gas, it is possible to improve the drying efficiency.
According to the sixth feature of the invention, the cleaning and drying method of the first feature is further characterized in that said dry gas is supplied into said drying chamber to create an atmosphere of dry gas during executing the first drying process, previously to the second drying process. Thus, since the object transported into the drying chamber is in the atmosphere of the dry gas, it is possible to shorten the second drying period and reduce the consumption of the dry gas.
According to the seventh feature of the invention, there is also provided a cleaning and drying apparatus for cleaning and drying an object to be processed, said apparatus including:
a cleaning chamber storing cleaning liquid, said cleaning chamber being constructed so as to drain said cleaning liquid through a lower portion of said cleaning chamber;
a drying chamber positioned above said cleaning chamber;
moving means for moving said object between said cleaning chamber and said drying chamber;
at least one dry-gas nozzle arranged in said drying chamber;
closing means arranged between said cleaning chamber and said drying chamber, for allowing said cleaning chamber and said drying chamber to be insulated from each other; and
control means for controlling operations of said dry-gas nozzle and said closing means. With the above-mentioned arrangement, the dry gas can be effectively utilized thereby to down-size the apparatus.
According to the eighth feature of the invention, there is also provided a cleaning and drying apparatus for cleaning and drying an object to be processed, said apparatus including:
a cleaning chamber storing cleaning liquid, said cleaning chamber being constructed so as to drain said cleaning liquid through a lower portion of said cleaning chamber;
a drying chamber positioned above said cleaning chamber;
moving means for moving said object between said cleaning chamber and said drying chamber;
at least one first dry-gas nozzle arranged in said drying chamber;
closing means arranged between said cleaning chamber and said drying chamber, for allowing said cleaning chamber and said drying chamber to be insulated from each other; and
at least one second dry-gas nozzle arranged in said cleaning chamber.
With the above-mentioned arrangement, the dry gas can be utilized effectively, so that it is possible to improve the drying efficiency and additionally, the efficiency in the cleaning and drying processes can be improved. Further, since the above arrangement allows the drying chamber to be down-sized in capacity, thereby miniaturizing the apparatus itself.
According to the ninth feature of the invention, the above-mentioned cleaning and drying apparatus of the eighth feature is characterized by further control means for controlling operations of said first and second dry-gas nozzles and said closing means. Thus, the dry gas can be utilized effectively, so that it is possible to improve the drying efficiency and additionally, the efficiency in the cleaning and drying processes can be improved.
The above and other features and advantages of this invention will become apparent, and the invention itself will best be understood from a study of the following description and appended claims, with reference to the attached drawings showing preferred embodiments of the invention.